Received: 9 May 2019
Accepted: 6 November 2019
First Online: 21 November 2019
Ethics approval and consent to participate
: The Faculty of Dentistry/ Faculty of Pharmacy, Mahidol University, Institutional Review Board reviewed the protocol and granted the ethics approval to access the available aggregated patient data from the PCS, owned by the DOH Philippines. The DOH Philippines also released a certification to allow the use of the aggregated survival data for the sole purpose of this study.
: Not applicable
: The authors declare that they have no competing interests.